This invention pertains to the field of rotary cutters more specifically to the field of cutters adapted for separating bark from the hardwood of a tree.
In the field of sawmill operation it is necessary, as one of the steps for preparing a tree for further use that the outer bark coating of the tree be separated from the tree. While the technology appears to draw from the field of wood chippers and adzes, it is distinct in that while it is necessary to remove the bark by abrading, it is deleterious to the tree to cut significantly into the wood. Thus a cutting head or adz which is equally adapted to chipping wood as well as bark is unsatisfactory for the use.
Two major forms of debarkers are in common use. Typically each depends upon the fact that the shear strength of the bark is weakest in the cambium layer between the wood and the bark.
Once such form of machine is known as the hollow rotor type in which a plurality of arms, swing mounted to a rotary collar extend inward scraping tangentially in a spiral around the exterior of the tree which is fed through the center of the collar. Typical such cutters are shown in U.S. Pat. No. 4,231,406 to Jonsson and U.S. Pat. No. 4,709,737 to Jonsson.
More commonly used form of debarker is the so-called rosser-head debarker in which a log is traversed past a rotating cylindrical cutter head which rotates against the log, parallel to the axis of the log. As the log is rotated against the head various forms of cutters upon the rosser-head are depended upon to tangentially shear the bark from the log. Typical such prior constructure shown in the Salem rosser-head debarker and the debarkers manufactured by Fulghum Industries, and the Forest Tool Company.
A typical debarker of the radial arm type is manufactured by Valone, Kone, Brunette, Inc.